1. Field of the Invention
Mulching is the practice of applying foreign materials to a seedbed to reduce erosion and provide a more favorable microenvironment for seed germination and seedling development. On level planting beds where the capability for frequent irrigation exists, mulching may not be necessary during propagation. However, mulching can enhance germination and it is almost essential on sloping sites or where moisture availability largely depends on natural rainfall.
An effective mulch serves several functions: it stabilizes the soil and seed against water and wind erosion; it moderates temperature fluctuations at the soil surface and thus protects germinating seeds and seedlings from temperature-induced injury; it reduces evaporation of moisture from the soil surface and provides a more humid microenvironment in and directly above the soil surface, and it dissipates the energy of falling water droplets from rainfall and irrigation to reduce crust formations at the soil surface and thus water infiltration rates are not decreased. Not all mulches serve all of these functions; some are more effective than others, and selection of a particular material depends on the specific requirements at each site and the cost and local availability of materials.
2. Discussion of the Prior Art
For decades, one of the most widely used mulches has been straw, primarily from wheat plantings. Applied at a rate of 1.5-2.0 tons per acre, it provides acceptable results. Weed-free straw should be used, and as long as coverage is not too heavy (not more than 50 percent soil coverage), the straw need not be removed after seedling emergence.
Grassy hay is similar to straw in its effectiveness as a mulch. Early-season cuttings of hay are preferred, as they are less likely to contain substantial populations of weed seeds.
Straw and hay can be applied by hand to small sites. In windy areas, they should be stabilized by crisscrossing the area with binder twine anchored down with stakes. Application to large sites is usually accomplished by using a mechanical mulch blower. This machine chops the material and blows it over the seedbed. An asphalt binder is usually sprayed on the mulch as it exits the blower, or after application, to stabilize the mulch on the seedbed. The same technique can be used for loose wood mulches and organic residues. Typically straw contaminates the seedbed with weed seeds and depletes the seedbed of nitrogen, due to the high C:N ratio of straw.
Hydro-mulch is another mulch commonly used for turfgrass establishment. Hydro-mulch can be made from virgin wood fibers, waste paper fiber from various industries, or newsprint. Although hydro-mulch can be stored and is weed free, it requires the use of a hydro-mulcher, which is an expensive piece of equipment, for application. Hydro-mulching also requires the availability of a very large water source, near the application site, to service the hydro-mulching process.
Reference is made to U.S. Pat. No. 3,269,824 which discloses a process for repulping waste paper of various types into a slurry, adding thereto fertilizer minerals including nitrogen, potassium, phosphorous, etc., drying under vacuum and stamping into dense pellets useful for application as a mulch. Repulping a waste paper requires large amounts of water and expensive equipment, and produces large volumes of contaminated waste water. Also the densified pellets require large amounts of absorbed moisture before expanding to increase ground coverage and to release nutrients.
Reference is also made to U.S. Pat. No. 4,339,890 which discloses a dry seeding hydro-mulch containing shredded or ground particles of waste paper and dry wetting agent, which is sprayed onto the soil after mixing it with water in a hydro-mulcher. Such equipment is expensive and requires access to substantial amounts of water.
Reference is also made to U.S. Pat. No. 4,369,597 which relates to the formulation of pelletized mint mulch suitable for application as a hydro-mulch or in dry form, and which discusses the disadvantages of the waste paper mulch pellets of U.S. Pat. No. 3,269,824, discussed supra. Finally, reference is made to U.S. Pat. Nos. 4,123,489; 4,625,679; 4,813,996 and 5,195,465 for their disclosure of processes for pelletizing waste paper particles containing soil nutrients and other ingredients for various uses including soil additives and mulches.